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28/03/2017

In a recent post I ran through setting a Raspberry Pi as a DMR hotspot using a DVMega and MMDVMHost.MMDVMHost natively supports various displays including various TFT's manufactured by Nextion, 128x64 OLED screens commonly seen in Arduino projects, and HD44780 based LCD displays.I wanted something colourful but still compact, so I went with a 2.4" Nextion screen available on Ebay here for around £12.50. Shipping from China took just over 2 weeks which is satisfactory.I also required a USB to Serial adapter to drive the display, as the Raspberry Pi's built in serial port was already being used to control the DVMega. This was purchased from Ebay here for £2.70.

20/03/2017

The Raspberry Pi 3 has a built in Wifi chip, which supports client mode (Connecting to a network) and access point mode (Hosting the network other clients connect to). It can also do these simultaneously, allowing the Pi to connect to a network via Wifi (Or Ethernet, or 3G) and share its connection with other devices.

This can be useful in the case of public Wifi that requires some kind of login or registration. As I run my Pi 'headless', I can't authenticate via the Pi itself, but I can now connect to the Pi's access point and go through the registration process. It also means on networks that block client-to-client communication, a device can still access services hosted on the Pi and still access the internet.

19/03/2017

In my previous post I provided a tutorial for setting up a DVMega and Raspberry Pi to use as a DMR hotspot.

The DVMega can also be used in a bluetooth only configuration where the heavy lifting is done my another device, such as an Android or iOS handset. The bluetooth hardware seems to go by a few different names but can be purchased here. The software to do this was previously called openSpot, but has been renamed blueDV.

As I have already got the DVMega and Raspberry Pi 3 package, I thought I'd have a go at 'converting' it to be suitable for use with blueDV. I found some information on doing this on G0WFV's blog, which sets up ser2net so blueDV can communicate over 'serial' over Ethernet.

Some of the steps were already performed prior to installing MMDVMHost, so I've added the modified steps below.

12/03/2017

NOTE: This post is now a year old. MMDVM is a fast moving target, and raspbian has since been updated, so these instructions may be out dated. I throughly suggest you use the Pi Star image instead.

To celebrate passing my foundation radio license I treated myself to a Connect Systems CS-580 DMR Radio. DMR (Digital Mobile Radio) is a digital standard that digitises and compresses the audio, allowing two simultaneous conversations to occupy the same amount of bandwidth as a single narrow band call using a traditional FM radio. There's a lot more to it than than, but it's probably best covered in another post.

Unfortunately I discovered signal strength from my local DMR repeater GB7WL was marginal, so I was unable to pick it up from the warmth and comfort of my flat. I initially considered fitting an external aerial, but that would leave me unable to roam around my flat as I'd be tethered via a cable to the aerial, so I started looking into hotspots - a low powered radio device that connects into the existing DMR networks over the internet and relays the voice traffic out of a small antenna. Plus, as I passed my intermediate license in the time it took for the CS-580 to arrive, I was due another treat...

I've heard good things about the SharkRF openSpot, a hotspot that works 'out of the box', but the inner hacker in me wanted something a little more customisable. I then stumbled across the DVMega, an add on 'shield' for the Raspberry Pi, and decided it would better suit my needs. The DVMega + Raspberry Pi also came out at approximately £150, which is £50 cheaper than the openSpot and includes a Pi that I can continue to use if I move on from DMR radio.

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